The disclosure relates to a solenoid valve with a valve body, the valve body having provided in it a valve seat closable by means of a sealing element, at least one outlet duct issuing into a fluid space, receiving the sealing element at least in regions, of the solenoid valve, and a flow guide element surrounding the sealing element at least in regions, the sealing element being operatively connected to a magnet armature arranged in a magnet armature space formed on a side of the flow guide element which faces away from the fluid space. The disclosure relates, furthermore, to a driver assistance device.
Solenoid valves of the type initially mentioned are known from the prior art. Solenoid valves of this type, for example currentlessly closed 2/2-way solenoid valves or else currentlessly closed 2/2-way solenoid valves, can be used in ABS, TCS or ESP systems. The solenoid valves have a valve seat which is closable by means of a sealing element. For this purpose, the sealing element is displaceable at least between a closing position and a releasing position. In the closing position, the sealing element is arranged in such a way that it covers the valve seat and therefore closes it. In the releasing position, the sealing element is, for example, spaced apart from the valve seat, so that fluid can pass through the valve seat. In the closing position, the solenoid valve is impermeable to the fluid, whereas, in the releasing position, this fluid can flow through the solenoid valve. The sealing element is arranged at least in regions in the fluid space of the solenoid valve. The valve seat may also be present in a wall of the fluid space. Moreover, the at least one outlet duct issues into the fluid space, and there may be a permanent fluid connection between the fluid space and the outlet duct. Fluid can be supplied to the solenoid valve via an inlet duct, this fluid being conveyed toward the valve seat via the inlet duct. When the sealing element is in the releasing position, the fluid can pass through the valve seat into the fluid space and subsequently be discharged from this via the outlet duct.
In the releasing position, the sealing element is usually arranged above the valve seat, so that the fluid flowing through the valve seat flows onto said sealing element or onto a magnet armature connected to it. Moreover, the flow direction of the inflowing fluid often points away from the outlet duct, so that the fluid is first braked in the fluid space before it can flow into the outlet duct. In this case, it may also happen that the fluid passes into regions between the magnet armature and a housing of the solenoid valve. Both the flow of the inflowing fluid onto the sealing element and/or onto the magnet armature and the fluid penetrating between the magnet armature and housing influence the displaceability of the sealing element, since the fluid applies an additional axial force to the sealing element or to the magnet armature connected to the sealing element. This may sometimes adversely affect the actuation quality of the solenoid valve. This is because this additional force influences the equilibrium of forces between a restoring force of a spring element and a magnetic force which serves for displacing the sealing element and which acts on the magnet armature, and a fluid pressure force which is taken into account in the design of the solenoid valve. This is the case particularly in solenoid valves in which a mouth of the outlet duct in the fluid space is arranged next to the valve seat, so that the inflow of the fluid through the valve seat and outflow through the outlet duct take place in opposite directions.
It would basically be advantageous if, instead of the additional forces acting in the axial direction upon the sealing element or magnet armature, only rotationally symmetrical radial forces were to occur, because these have no influence upon the axial equilibrium of forces. For this reason, a flow guide element may be provided which, for example, has a flow guide surface, by means of which inflowing fluid is deflected in the direction of the outlet duct or is conveyed toward the latter. The flow guide surface may in this case be curved at least in regions, advantageously in the direction of the outlet duct. The flow guide element in this case separates the magnet armature space from a fluid space of the solenoid valve in which the valve seat is arranged. The magnet armature, to which the sealing element is operatively connected, is arranged in the magnet armature space. By virtue of this operative connection, the sealing element can be displaced by means of the magnet armature, this being provided at least between the closing position and the releasing position.
A solenoid valve of this type is known, for example, from DE 198 02 464 A1. This shows a hydraulically magnet-actuated valve with a guide body for pressure medium which is arranged in the housing of the solenoid valve and which is penetrated by a closing body and separates an annular duct connected conductively to a valve seat pressure medium and having at least one circumferential outlet port of the valve housing from a space containing actuating means of the valve. In this case, the guide body is to be supported on the valve body by bearing against the end face of the latter and is to have guide ducts which overlap with their contour the mouth-side valve seat and which issue on the outflow side into the annular duct. In known solenoid valves, pressure compensation or fluid exchange between the fluid space and magnet armature space is brought about by means of an orifice of the flow guide element, in which orifice the sealing element is arranged or guided at least in regions.